As is well known, a vehicle is comprised of one or more differential gears and each of them is comprised of a differential gear set for allowing output shafts to make differential motion, which transmits torque put into a differential case to the pair of output shafts for example.
How to install a differential gear set and a pinion shaft combining the gear set with a case into the case is a problem. One solution is to make the case dividable into plural pieces and, by dividing it, provide a wide opening for installation with the case. This solution, however, creates some drawbacks in cost and weight as it causes an increase in a number of parts and necessitates additional parts for combining them. Another solution is to form a wide entrance on an outer periphery of the case of a single piece and bring the gear set into the interior therethrough.
The following documents disclose related art.                Japanese Patent Application Laid-open No. H11-30315        U.S. Pat. No. 7,780,565        